Security method of mobile internet protocol based server

ABSTRACT

A security method in a server-based mobile IP system is provided. Specifically, in the security method, general data is securely exchanged in addition to a control message that is exchanged between a mobile node and a server or between mobile nodes. Specifically, provided is a method of securely exchanging data by using a mobile node including an mPAK execution module generating necessary keys by exchanging key information with the server while performing a mutual authentication process and negotiating the security policy; and a security module setting a security policy that is negotiated with the corresponding node and applying the security policy to data according to the set security policy when transmitting the data.

TECHNICAL FIELD

The present invention relates to a security method in a server-basedInternet protocol (IP) system, and more particularly, to a securitymethod for securely exchanging general data in addition to a controlmessage that is exchanged between a mobile node and a server or betweenmobile nodes.

The present invention is supported by the IT R&D program ofMIC/IITA[2007-S-013-01, R&D on all IPv6 based Fixed-Mobile convergencenetworking technology].

BACKGROUND ART

General methods used to protect data that is exchanged between two nodesare an IP security protocol (IPSEC) method and a transport layersecurity (TLS) method. The IPSEC method is essential for security of acontrol message in a mobile IP that is suggested by the InternetEngineering Task Force (IETF). An IPSEC is constructed with an Internetkey exchange (IKE) for performing a key exchange function in a userarea, an authentication header (AH) for protecting data in a kernelarea, and an encapsulating security payload (ESP). Since a message isprotected from an IP header, it is impossible to protect data for eachservice application or to apply quality of service (QoS). On thecontrary, in the TLS method, it is possible to protect data for eachapplication, and however, it is impossible to perform a securityfunction for the IP header.

In order to protect data, the two nodes have to share the same keyinformation. In order to share the same key between the two nodes, theIPSEC uses the IKE, and the TLS uses a key exchange function of its own.A mutual authentication process between the two nodes is essential toperform the key exchange function. A certificate is mainly used for thismutual authentication process. That is, a key is necessary for securityof data. The certificate is needed so as to exchange the key. A securityinfrastructure such as a public key infrastructure is needed so as tomanage the certificate. In addition, since the key exchange protocol hasa considerably complex structure, it is difficult to apply the keyexchange protocol to a wireless environment.

DISCLOSURE OF INVENTION Technical Problem

The present invention provides a method of protecting various messagesto be exchanged between nodes through a key exchange method suitable fora wireless environment by using a simple protocol without a certificatein a server-based mobile IP system.

The present invention also provides a filtering function in addition toa message security function by supporting a 5-tulpes lookup process soas to protect a message.

Technical Solution

According to an aspect of the present invention, there is provided asecurity method of a mobile node in a server-based mobile IP system, thesecurity method comprising: generating a tunnel with a server by using afirst security component exchanged by performing a mobile password-basedauthentication key exchange (mPAK) process with the server; transmittinga pseudo password query message (PPQ) to the server through thegenerated tunnel; exchanging a second security component by performingthe mPAK process with a destination node by using a pseudo passwordacknowledgement message (PPA) received from the server in response tothe PPQ; and generating a tunnel for security of data and a controlmessage that is transmitted and received to and from the destinationnode by using the second security component.

According to another aspect of the present invention, there is provideda security method of a mobile node in a server-based mobile IP system,the security method comprising: generating a tunnel by using securitycomponents that are exchanged by performing a mPAK process with aplurality of mobile nodes; receiving a PPQ from at least one mobile nodethrough the generated tunnel; and transmitting a pseudo password, whichis generated as a random number is generated, to the mobile node whenreceiving the PPQ.

According to another aspect of the present invention, there is provideda mobile node device in a server-based mobile IP system, the mobile nodedevice comprising: an mPAK execution module generating necessary keys byexchanging key information with the server while performing a mutualauthentication process and negotiating the security policy; and asecurity module setting a security policy that is negotiated with thecorresponding node and applying the security policy to the dataaccording to the set security policy when transmitting data.

Advantageous Effects

As described above, in the server-based mobile IP system, it is possibleto reduce a large amount of operations and the number of processes ofexchanging messages and to perform a secure communication process in amobile node having low power and computational capability by using asimple protocol without using an infrastructure such as anauthentication center so as to exchange a key.

In addition, it is possible to apply a security policy for eachapplication by determining a security policy through a 5-tuple lookupprocess and to perform a function of a simple fire wall by applying apacket filtering technique.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates security procedures between a node and a server andbetween nodes in a server-based mobile IP system according to anembodiment of the present invention.

FIG. 2 illustrates the security procedures of FIG. 1 in detail.

FIG. 3 illustrates a detailed method of executing a security process ofdata according to an embodiment of the present invention.

FIG. 4 illustrates a format of data that is transmitted and receivedaccording to a security policy according to an embodiment of the presentinvention.

FIG. 5 illustrates a procedure of ciphering data according to anembodiment of the present invention.

FIG. 6 illustrates a procedure of deciphering data according to anembodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. In the description of the present invention, if itis determined that a detailed description of commonly-used technologiesor structures related to the invention may unnecessarily obscure thesubject matter of the invention, the detailed description will beomitted.

In an embodiment of the present invention, a mobile password-basedauthenticated key exchange (hereinafter, referred to as mPAK) process isused. The mPAK process indicates a process of exchanging a key by usinga password. In the mPAK process, it is possible to securely exchange akey without a security infrastructure such as a public keyinfrastructure (PKI). That is, when a mobile node is turned on or when amobile service is to be used, in a server-based mobile IP system, a keyis exchanged between a mobile node and a server by allowing a user toinput an ID and a password. Thus, a message is protected by using theexchanged key. Here, the exchanged key is available until the mobilenode is turned off or until the mobile service is stopped.

A security method for protecting control messages in a server-basedmobile IP system will be described with reference to the attacheddrawings. First, a procedure of exchanging a key by using the mPAKprocess in the server-based mobile IP system will be described.

FIG. 1 illustrates security procedures between a mobile node and aserver and between mobile nodes in a server-based mobile IP systemaccording to an embodiment of the present invention.

Referring to FIG. 1, in the server-based mobile IP system, mobile nodes10 a and 10 b exchange security components by performing the mPAKprocess with a server 20 and generate secure tunnels by using theexchanged security components (operation 101). When the secure tunnelsare generated, the mobile nodes 10 a and 10 b and the server 20 transmitand receive a control message while sharing information according to amessage security method (operation 102).

As described above, after a security procedure is performed between themobile nodes 10 a and 10 b and the server 20, a procedure ofcommunicating data between the mobile nodes may be performed. A localnode 10 a which desires to communicate data transmits a pseudo passwordquery (PPQ) message to the server 20 so as to set a secure tunnel with aremote node 10 b that is a destination node of data communication(operation 103).

The server 20 generates a pseudo password according to the PPQ of thelocal node 10 a and transmits the pseudo password to the local node 10 aand the remote node 10 b (operations 103 and 104).

When the pseudo password is received from the server 20, the securetunnel between the local node 10 a and the remote node 10 b is generatedby performing the mPAK process by using the received pseudo password(operation 105). When the secure tunnel between the local node 10 a andthe remote node 10 b is generated, data and a control message areexchanged through the tunnel generated between the two nodes (operation106 and 107).

FIG. 2 illustrates the security procedures of FIG. 1 in detail. Theaforementioned security procedure will be described in detail withreference to FIG. 2.

In a case where each of the mobile node 10 a and 10 b is turned on or acase where a user who desires to receive a mobile service exists, theuser inputs an identification (ID) and a password (PW). When the ID andthe PW are input by the user, first and second mobile nodes 10 a and 10b exchange information for setting a secure tunnel between the firstmobile node 10 a and the server 20 and information for setting a securetunnel between the second mobile node 10 b and the server 20 byperforming the mPAK process with the server 20, respectively (operation201). Specifically, the mobile nodes 10 a and 10 b negotiate securitypolicies and components required so as to exchange a key, mutuallyauthenticate each other, and set secure tunnels by performing the mPAKprocess with the server 20.

Information on the key to be exchanged through the mPAK process becomesa seed of the key. Various keys may be generated by using the key seed.However, the various keys may be generated through various knownmethods.

In addition, information that is shared by the mobile nodes 10 a and 10b and the server 20 through the negotiation may be applied in variousmanners according to the message security method. For example, in a casewhere an authentication header (AH) and an encapsulating securitypayload (ESP) of an IP security protocol (IPSEC) are used, it isnecessary to negotiate information for setting security associationaccording to a security policy. Setting of security associationaccording to the security policy indicates setting of a security policydatabase (SPD) for a secure tunnel and a security association database(SAD).

Here, security parameter indices (hereinafter, referred to as SPI), anaddress and a port number of a source, an address and a port number of adestination, information on whether the AH and the ESP are used,information on whether a mode is a transport mode or tunnel mode, acipher/decipher algorithm and key, an authentication algorithm and keyare necessary so as to set the security association.

When an exchange of the information for generating the secure tunnel iscompleted by performing the mPAK process between the mobile nodes 10 aand 10 b and the server 20, a security tunnel is set between the mobilenodes 10 a and 10 b and the server 20 (operation 202).

When secure tunnels between the mobile nodes 10 a and 10 b and theserver 20 are generated, subsequent control messages to be exchangedbetween the mobile nodes 10 a and 10 b and the server 20 are transmittedthrough the secure tunnels (operation 203). The secure tunnels may beseparately generated according to types of control messages.Alternatively, only a secure tunnel may be generated regardless of thetypes of control messages.

When information to be protected exists in an IP header of a controlmessage to be exchanged between the mobile nodes 10 a and 10 b and theserver 20 through the generated security tunnels, a security function isperformed by using the AH and the ESP of the IPSEC. Alternatively, wheninformation to be protected does not exist in the IP header, varioustypes of security methods may be applied if necessary. For example, ifonly authentication of a control message to be exchanged is necessary, atunnel may be set through a Keyed Hash method. In addition, a tunnel maybe set so as to perform an authentication function, a cipher function,and a decipher function if necessary. However, the type of controlmessages to be exchanged may be determined if necessary. Here, the typeof control messages is not additionally described.

In a case where the first mobile node 10 a desires to communicate datawith the second mobile node 10 b after a secure tunnel is generated, thefirst mobile node 10 a transmits a pseudo password query (PPQ) messageto the server 20 through the generated secure tunnel (operation 204). Atthis time, the PPQ message includes an address of a destination nodewith which data is to be communicated. Here, the destination nodeindicates the second mobile node 10 b.

When the server receives the PPQ message from the first mobile node 10a, the server generates a pseudo password which is used instead of apassword that is an input parameter of the mPAK process (operation 205).Specifically, the server generates a random number according to arequest of the first mobile node 10 a and generates a pseudo password byusing the generated random number. Here, a method of generating therandom number may be a general random number generation method. Inaddition, the requested pseudo password includes a pseudo ID and apseudo password.

The server 20 transmits a pseudo password acknowledgement message (PPA)including the pseudo password generated through the generated securetunnel to the first mobile node 10 a after generating the pseudopassword (operation 206) and transmits the PPA including the generatedpseudo password to the second mobile node 10 b that is the destinationnode (operation 207).

At this time, the PPA transmitted from the server 20 to the first andsecond mobile nodes 10 a and 10 b includes information on the generatedpseudo ID and the pseudo password.

The first and second mobile nodes 10 a and 10 b perform the mPAK processby using the pseudo password transmitted from the server for securecommunication (operation 208). Here, the mPAK process is the same as themPAK process performed by using a password between the aforementionedmobile nodes and the server.

A secure tunnel for securely exchanging data and control messages isgenerated between the first and second mobile nodes 10 a and 10 b afterperforming the mPAK process (operation 209).

Accordingly, the first and second mobile nodes 10 a and 10 b exchange acontrol message through a secure tunnel (operation 210) and exchangedata to be exchanged between applications (operation 211).

The mPAK process is performed through an mPAK protocol shown in Table 1.Hereinafter, Table 1 will be described in detail.

Brief description on symbols shown in Table 1

-   -   H[ ]: Hash function    -   LA∥RA∥ID∥PW: Local address∥Remote address∥ID∥password (∥        indicates concatenation).    -   PRF[ ]: pseudo random number generation function    -   KH[ ]_(K): Keyed Hash by using key K

A message exchanged for each node may be defined according to a messagesecurity method. For example, in a case where a message security methodis the IPSEC, items such as various available security algorithms, atype for distinguishing ESP/AH, a mode for distinguishing atransport/tunnel mode, and the like are included in the message MSG_(R),MSG_(L), and MSG_(N) and negotiated.

TABLE 1 Local Node Remote Node x∈_(R)Z_(q) m = g^(x) mod P X = m ·H[LA∥RA∥ID∥PW] $\quad\begin{matrix}\; \\\underset{\rightarrow}{{ID},X}\end{matrix}$ $\quad\begin{matrix}\; \\\; \\\; \\\; \\\underset{\leftarrow}{{ID},Y,\;{MSG}_{R},{AUTH}_{R}}\end{matrix}$ $\quad\begin{matrix}{{y\text{∈}_{R}Z_{q}},{\mu = {g^{y}\mspace{11mu}{mod}\mspace{11mu} P}}} \\{\sigma = {\left( \frac{X}{H\left\lbrack {{LA}{{{RA}{{{ID}\left. {PW} \right\rbrack}}}}} \right.} \right)^{y}\mspace{11mu}{mod}\mspace{11mu} P}} \\{{\mspace{14mu}\;}{= {g^{xy}\mspace{11mu}{mod}\mspace{11mu} P}}} \\{K_{seed} = {H\left\lbrack {{LA}{{{RA}{{{ID}{{{PW}{{m{{\mu\left. \sigma \right\rbrack}}}}}}}}}}} \right.}} \\{K_{A} = {{PRF}\left\lbrack {K_{seed}{{\sigma{{{ID}{{{PW}\left. 0 \right\rbrack}}}}}}} \right.}} \\{Y = {\mu \cdot {H\left\lbrack {{LA}{{{RA}{{{ID}\left. {PW} \right\rbrack}}}}} \right.}}} \\{{AUTH}_{R} = {{KH}\left\lbrack {{ID}{{Y\left. {MSG}_{R} \right\rbrack_{K_{A}}}}} \right.}}\end{matrix}$ $\quad\begin{matrix}{\sigma = {\left( \frac{Y}{H\left\lbrack {{LA}{{{RA}{{{ID}\left. {PW} \right\rbrack}}}}} \right.} \right)^{x}\mspace{11mu}{mod}\mspace{11mu} P}} \\{{\mspace{14mu}\;}{= {g^{xy}\mspace{11mu}{mod}\mspace{11mu} P}}} \\{K_{seed} = {H\left\lbrack {{LA}{{{RA}{{{ID}{{{PW}{{m{{\mu\left. \sigma \right\rbrack}}}}}}}}}}} \right.}} \\{K_{A} = {{PRF}\left\lbrack {K_{seed}{{\sigma{{{ID}{{{PW}\left. 0 \right\rbrack}}}}}}} \right.}} \\{{Verify}\mspace{14mu}{AUTH}_{R}} \\{{AUTH}_{L} = {{KH}\left\lbrack {{ID}\left. {MSG}_{L} \right\rbrack_{K_{A}}} \right.}}\end{matrix}$ $\quad\begin{matrix}\; \\\; \\\; \\\; \\\; \\\; \\\underset{\rightarrow}{{ID},{MSG}_{L},{AUTH}_{L}}\end{matrix}$                   Verify AUTH_(L) Verify AUTH_(N)$\underset{\leftarrow}{{ID},{MSG}_{N},{AUTH}_{N}}$ AUTH_(N) =KH[ID∥MSG_(N)]_(K) _(A)

A procedure of exchanging a key according to the mPAK protocol will bedescribed in detail.

A local node which initially desires to exchange a key selects a randomnumber x and calculates X by using the selected random number. At thistime, the random number x is used to generate a key as secretinformation.

A remote node which receives information searches for a password byusing the received ID. It is assumed that information on the ID and thepassword is previously known by the local node through a previousprocedure. The remote node selects a random number y, calculates and,and calculates a seed K_(seed) that is used to generate a key by usingthe calculated information. A key K_(A) for applying the Keyed Hash to amessage MSG_(R) is calculated, and AUTH_(R) is calculated by using thecalculated information. Here, the message MSG_(R) may include varioustypes of information according to a security method.

If the applied security method is IPSEC, the MSG_(R) includes thefollowing information.

MSG_(R)=[cipher_alg_num, cipher_alg_list, mac_alg_num, mac_alg_list,type, mode, proto, dhGroup, SPI, local_addr_v4, local_addr_v6]

The MSG_(R) includes a list of various security algorithms which can besupported by the remote node. Here, cipher_alg_num indicates the numberof available cipher algorithms, cipher_alg_list indicates a list ofavailable cipher algorithm, mac_alg_num indicates the number ofavailable authentication algorithms, and mac_alg_list indicates a listof available authentication algorithms. The MSG_(R) includes informationon items such as type for distinguishing ESP/AH, mode for distinguishinga transport/tunnel mode, proto for indicating a protocol, dhGroup forindicating a Diffie-Hallman group, SPI for distinguishing SA, and thelike. In addition, local_addr_v4 and local_addr_v6 indicate an IPv4address and an IPv6 address of the remote node, respectively.

In addition, a security method in which the MSG_(R) includes thefollowing information may be applied.

MSG_(R)=[cipher_alg_num, cipher_alg_list, mac_alg_num, mac_alg_list,local_addr_v4, local_addr_v6]

A local node which receives a message from a remote node calculates byusing secret information x, calculates a key seed K_(seed) and a keyK_(A) for authentication, and verifies the received AUTH_(R). If theverification is successful, a message MSG_(L) is generated, and AUTH_(L)is calculated by using the authentication key K_(A).

Here, the generated message MSG_(L) may be differently applied accordingto a security method.

For example, in a case where, the security method is the IPSEC, themessage MSG_(L) is represented as follows.

MSG_(L)=[cipher_alg, mac_alg, type, mode, SPI]

An algorithm having a high priority is determined by comparing a list ofsecurity algorithms obtained from the MSG_(R) that is received from theremote node with a list of algorithms which can be supported by theMSG_(R) and transmitted to the remote node.

In addition, the MSG_(L) may include the following information accordingto another security method.

MSG_(L)=[cipher_alg_num, cipher_alg_list, mac_alg_num, mac_alg_list,sp_num, sp_info[action, proto, dport, sport, cipher_alg, mac_alg]]

At this time, the message MSG_(L) includes information on variousavailable security algorithms and information on a security policy.Here, meanings of cipher_alg_num, cipher_alg_lit, mac_alg_num, andmac_alg_list are the same as those in the MSG_(R). Here, sp_numindicates the number of security policies. The security policiesincludes items such as action for indicating add/delete, proto forindicating a protocol, dport for indicating a destination port number,sport for indicating a source port number, cipher_alg for indicating acipher algorithm, mac_alg for indicating an authentication algorithm,and the like. The cipher algorithm and the authentication algorithm aredetermined according to priorities among security algorithms which canbe supported by both nodes by comparing algorithms that can be supportedby the remote node with algorithms that can be supported by the localnode.

The remote node verifies the received AUTH_(L). When the verification issuccessful, information on whether the verification is successful istransmitted to the local node through the message MSG_(N).

Next, in a case where the security method is the IPSEC, the messageMSG_(N) is represented as follows.

MSG_(N)=[result]

In addition, in a case where another security method is used, themessage MSG_(N) may include the following information.

MSG_(N)=[sp_num, sp_info[action, proto, dport, sport, cipher_alg,mac_alg]].

Here, a meaning of each field is the same as that of MSG_(L).

The messages MSG_(R), MSG_(L), and MSG_(N) may include various types ofinformation according to a security method applied to a message in asecurity module.

After performing a procedure shown in Table 1, the two nodes can sharethe key seed K and generate various types of keys by using the key seed.Since methods of seed generating various keys by using a key seed areknown, the methods are not described in this specification.

FIG. 3 illustrates a detailed method of executing security of dataaccording to an embodiment of the present invention.

Each node shares a key through an mPAK protocol 30 a so as to transmitdata and a control message through a secure tunnel between the two nodesand includes a security module 30 c which applies a security policy totransmitted and received data.

In FIG. 3, the mPAK protocol 30 a indicates a protocol for performing anexchange of a key, and App(3b) indicates various types of applications.

As shown in FIG. 3, the security module 30 c which practically applies asecurity policy to data may separately operate. Alternatively, thesecurity module 30 c may be included in a Layer 2 network device driver.The security module 30 c which applies the security policy to data maydetermine whether to accept received data through a 5-tuple lookupprocess. This data filtering function is the same as a simple fire wallfunction.

In order to transmit and receive data and a control message between thetwo nodes according to the security policy, key information is exchangedby performing the mPAK 30 a by using an input password, and informationrelated to the security policy is transmitted to the security module 30c.

Information transmitted to the security module 30 c may includeinformation on cipher/decipher and authentication algorithms, a key, asequence number for preventing a replay attack, an informationgeneration time, a life time, and the like. An index for searching forthis information includes an address and a port number of a destination,an address and a port number of a source, and a protocol number. Themethod of performing the 5-tuple lookup process in the security module30 c may be selected from previously reported methods. The method ofperforming the 5-tuple lookup process is not described in detail in thisspecification.

In a case where data is exchanged between applications that exist in thetwo nodes through a secure tunnel generated by performing the mPAK 301,the exchanged data passes the security module 30 c after passing througha TCP/UDP layer 302 and an IP layer 303 and applies the security policyreceived from the mPAK 30 a to corresponding data. The data 304 to whichthe security policy is applied is transmitted to the destination nodethrough a public network.

When receiving data transmitted through the public network, thedestination node processes the data in the reverse order of the processin the node that transmits the data.

FIG. 4 illustrates a format of data that is transmitted and receivedbased on a security polity according to an embodiment of the presentinvention.

Specifically, Version 401 indicates a version, and Length 402 indicatesa length from Sequence Number 403 to Padding Length 408. The SequenceNumber 403 indicates a sequence number (8 bytes) for preventing a replayattack, and Initialization Vector (IV) 404 indicates an IV used for ablock cipher algorithm. Message 405 indicates data that is practicallytransmitted, MAC 406 indicates a result obtained by applying the KeyedHash, Padding 407 indicates a padding process needed for the blockcipher algorithm, and Padding Length 408 indicates a padding length.Fields such as the Version to the Message 401 to 405 performs anauthentication process by using Keyed Hash 409 and applies a dataencryption process 410 to fields such as the Message to Padding Length405 to 408. The used algorithms may use previously reported variousalgorithms.

FIG. 5 illustrates a procedure of ciphering data according to anembodiment of the present invention.

First, the 5-tuple lookup process is performed (operation S501), keyinformation and algorithm information needed to practically protect dataare searched for in addition to information such as Version, Length,Sequence Number, and IV as a result of the 5-tuple lookup process(operation S502).

Authentication information (MAC) is generated by using the Keyed Hash(operation S503), and Padding for ciphering data is performed after theMAC is generated (operation S504). Ciphering of data is performed(operation S505), and the ciphered data is transmitted (operation S506).

FIG. 6 illustrates a procedure of deciphering data according to anembodiment of the present invention.

When receiving data, the 5-tuple lookup process is performed, and it isdetermined whether to receive data based on the 5-tuple lookup result(operation 602). When receiving of the data is rejected, the currentprocess is terminated after an error message is returned and whenreceiving of the data is determined, a version is verified (operation603). When the version is valid as the result of verification of theversion, the Sequence Number is verified (operation 604). When theSequence Number is valid, the Padding for deciphering data is checked(operation 605). When the Padding is valid, the data is deciphered(operation 606). Alternatively, when the Version, the Sequence Number,and the Padding are not valid, the current process is terminated afteran error message is returned.

After deciphering data, an authentication process is performed bychecking the MAC (operation S607). When the authentication process issuccessful, the current process is terminated after the deciphered datais returned. Alternatively, when the authentication process is notsuccessful, the current process is terminated after an error message isreturned.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of thepresent invention as defined by the appended claims.

The invention claimed is:
 1. A security method of a mobile node in aserver-based mobile IP system, the security method comprising:exchanging, between a mobile node and a server, a first securitycomponent by performing a first password-based authentication keyexchange (PAK) process; generating a first secure tunnel between themobile node and the server; transmitting a pseudo password query message(PPQ) from the mobile node to the server through the first securetunnel; generating, at the server, a pseudo password acknowledgementmessage (PPA) in response to the PPQ; receiving, at the mobile node anda destination node, the PPA from the server; exchanging, between themobile node and the destination node, a second security component byperforming a second PAK process using the PPA; and generating a secondsecure tunnel between the mobile node and the destination node fortransmitting and receiving data and a control message, whereingenerating the first secure tunnel comprises: establishing a securitypolicy using the first security component exchanged by performing thefirst PAK process; and generating the first secure tunnel according tothe established security policy, wherein the established security policyuses a 5-tuple lookup process, and wherein key information, algorithminformation, a sequence number, a life time, and a generation time aresearched for as a result of the 5-tuple lookup process by using anaddress and a port number of a source, and an address and a port numberof a destination, and a protocol number as indices.
 2. The securitymethod of claim 1, wherein exchanging the first security componentcomprises allowing a user to input an identification (ID) and apassword.
 3. The security method of claim 1, wherein the first andsecond security components each include a security policy for exchanginga key, authentication, and generating a secure tunnel.
 4. The securitymethod of claim 1, wherein the PPQ includes an address of thedestination node.
 5. The security method of claim 1, whereinestablishing the first secure tunnel comprises: exchanging, between themobile node and the server, key information while performing a mutualauthentication process and negotiating a security policy; generatingnecessary keys by using the exchanged key information; and generatingthe first secure tunnel using the exchanged key information and thenegotiated security policy.
 6. The security method of claim 1, whereinthe PPA includes a pseudo ID and a pseudo password.
 7. A mobile nodedevice in a server-based mobile IP system, the mobile node devicecomprising: a password-based authentication key exchange (PAK) executionmodule configured to generate keys by exchanging key information with aserver while performing an authentication process, and negotiate asecurity policy; and a security module configured to set the securitypolicy that is negotiated with the corresponding node and applying thesecurity policy to data according to the set security policy whentransmitting the data, wherein the security module is configured tofilter data by applying 5-tuple lookup process, and wherein keyinformation, algorithm information, a sequence number, a life time, anda generation time are searched for as a result of the 5-tuple lookupprocess by using an address and a port number of a source, and anaddress and a port number of a destination, and a protocol number asindices.
 8. A security method of a mobile node in a server-based mobileIP system, the security method comprising: generating a tunnel by usingsecurity components that are exchanged by performing a password-basedauthentication key exchange (PAK) process with a plurality of mobilenodes; receiving a pseudo password query message (PPQ) from at least onemobile node through the generated tunnel; and transmitting a pseudo IDand a pseudo password in response to the PPQ, the pseudo ID and pseudopassword being generated by using as a random number, wherein generatingthe tunnel comprises establishing a security policy using the securitycomponents exchanged by performing the first PAK process and generatingthe tunnel according to the established security policy, and wherein theestablished security policy uses a 5-tuple lookup process, and whereinkey information, algorithm information, a sequence number, a life time,and a generation time are searched for as a result of the 5-tuple lookupprocess by using an address and a port number of a source, and anaddress and a port number of a destination, and a protocol number asindices.
 9. The security method of claim 8, wherein the PAK processcomprises allowing a user to input an ID and a password.
 10. Thesecurity method of claim 8, wherein the PPQ includes an address of asecond mobile node with which a first mobile node is to communicate. 11.The security method of claim 10, further comprising transmitting thepseudo password to the address of the second mobile node.
 12. The mobilenode device of claim 7, wherein the security module is included in aLayer 2 network device driver.
 13. The mobile node device of claim 7,wherein the security module includes a security policy database and asecurity association database.
 14. The security method of claim 1wherein the PPQ includes an internet protocol (IP) address of thedestination node.